U.S. patent application number 10/871230 was filed with the patent office on 2005-12-22 for electromechanical transducing.
Invention is credited to Breen, John J., Parison, James A..
Application Number | 20050280218 10/871230 |
Document ID | / |
Family ID | 35479838 |
Filed Date | 2005-12-22 |
United States Patent
Application |
20050280218 |
Kind Code |
A1 |
Parison, James A. ; et
al. |
December 22, 2005 |
Electromechanical transducing
Abstract
An electromagnetic transducer including a stator and an
armature, the armature defining a first axis and being driven to
ride between first and second couplers back and forth relative to
the stator along the first axis. The second coupler is configured
to permit movement of the armature along a second axis orthogonal
to the first axis.
Inventors: |
Parison, James A.;
(Framingham, MA) ; Breen, John J.; (Southborough,
MA) |
Correspondence
Address: |
FISH & RICHARDSON PC
P.O. BOX 1022
MINNEAPOLIS
MN
55440-1022
US
|
Family ID: |
35479838 |
Appl. No.: |
10/871230 |
Filed: |
June 18, 2004 |
Current U.S.
Class: |
280/5.5 ;
280/5.504 |
Current CPC
Class: |
B60G 2202/422 20130101;
H02K 41/02 20130101; H02K 2201/18 20130101; H02K 7/08 20130101;
B60G 17/0157 20130101 |
Class at
Publication: |
280/005.5 ;
280/005.504 |
International
Class: |
B60G 021/045 |
Claims
What is claimed is:
1. An apparatus comprising: an electromagnetic transducer including
a stator and an armature defining a first axis, wherein the
armature is driven to ride between first and second couplers back
and forth relative to the stator along the first axis; wherein the
second coupler is configured to permit movement of the armature
along a second axis, wherein the second axis is orthogonal to the
first axis.
2. The apparatus of claim 1 further comprising an outer case having
a first portion and a second portion.
3. The apparatus of claim 2 wherein the armature comprises first
and second ends, the armature being configured to be slidably
disposed within the case along the first axis.
4. The apparatus of claim 3 wherein the first coupler is configured
to couple the first end of the armature with the first portion of
the case and the second coupler is configured to couple the second
end of the armature with the second portion of the case.
5. The apparatus of claim 4 wherein the second coupler is
configured to impart high stiffness to the armature along a third
axis, orthogonal to both the first axis and the second axis.
6. The apparatus of claim 3 wherein the first coupler comprises a
first linear bearing rail attached to a first end of the armature
and a first bearing truck affixed to a first portion of the
case.
7. The apparatus of claim 3 wherein the first coupler comprises a
first linear bearing rail attached to a first portion of the case
and a first bearing truck affixed to a first end of the
armature.
8. The apparatus of claim 6 wherein the first bearing rail is
slideably disposed in the first bearing truck.
9. The apparatus of claim 6 wherein the first bearing truck is
aligned with the first end of the armature along a surface
substantially parallel to the first axis.
10. The apparatus of claim 3 wherein the second coupler comprises a
second linear bearing rail attached to the second end of the
armature, and a second bearing truck disposed within the second
portion of the case.
11. The apparatus of claim 10 wherein the second bearing truck
slideably engages the second portion of the case along the second
axis.
12. The apparatus of claim 10 further comprising set screws which
extend from at least one of the bearing trucks and ride within
slots disposed along the case to guide the movement of the
armature.
13. The apparatus of claim 10 wherein the second bearing truck
slideably engages a recess disposed in the second portion of the
case along the second axis for movement of the second end of the
armature along the second axis.
14. The apparatus of claim 3 wherein the second coupler further
comprises roller bearings positioned between the bearing surface
and the bearing pockets for slideable engagement of the second end
of the armature within the second portion of the case along the
second axis.
15. The apparatus of claim 3 wherein the second coupler further
comprises roller bearings positioned between the bearing surface
and the bearing pockets for rollable engagement of the second end
of the armature within the second portion of the case along the
first axis.
16. The apparatus of claim 3 wherein the second end of the armature
comprises a bearing surface, the bearing surface engaging a bearing
pocket disposed within the second portion of the case.
17. The apparatus of claim 3 further comprising roller bearings
positioned between at least one of the ends of the armature and the
case.
18. The apparatus of claim 3 wherein the couplers further comprise
low-friction blocks positioned between at least one of the ends of
the armature and the case.
19. The apparatus of claim 18 wherein the low-friction blocks
comprise delryn retainers.
20. The apparatus of claim 10 wherein the apparatus further
comprises a third coupler affixed to the second portion of the
case.
21. The apparatus of claim 20 wherein the third coupler comprises a
third bearing truck slideably coupled to the second bearing
rail.
22. The apparatus of claim 20 wherein the third coupler comprises a
surface substantially parallel to the first axis to provide
substantial alignment to the second coupler.
23. The apparatus of claim 20 wherein the third coupler comprises
at least one recess disposed along the second portion of the
case.
24. The apparatus of claim 3 further comprising a first biasing
element and a second biasing element extending from the second end
of the armature to the second portion of the case, the first
element providing a first stiffness along a third axis orthogonal
to the first axis and the second axis and the second element
providing a second stiffness along the second axis.
25. The apparatus of claim 24 wherein the at least one of the first
biasing element and the second biasing element comprises a spring,
a magnet, or an air bearing.
26. A vehicle having an active suspension system, a chassis and at
least one wheel assembly, the vehicle comprising at least one of
the apparatus of claim 1 for providing a controllable force between
the wheel assembly and the chassis, wherein the apparatus is
configured such that the first coupler of the armature
substantially faces the front of the vehicle and the second coupler
substantially faces the rear of the vehicle.
27. A vehicle having an active suspension system, a chassis and at
least one wheel assembly, the vehicle comprising at least one of
the apparatus of claim 1 for providing a controllable force between
the wheel assembly and the chassis, wherein the apparatus is
configured such that the asymmetry in the load capacity of the
couplers matches the asymmetry in the applied loads of the
vehicle.
28. A vehicle having an active suspension system, the vehicle
comprising: a chassis; at least one wheel assembly; and at least
one of the apparatus of claim 1 for providing a controllable force
between the wheel assembly and the chassis.
29. A vehicle having an active suspension system, the vehicle
comprising: a chassis; and at least two wheel assemblies; and each
wheel assembly comprising at least one of the apparatus of claim 1
for providing a controllable force between the wheel assembly and
the chassis.
30. An electromechanical transducer comprising: an outer case
having a first portion and a second portion and housing a stator;
an elongate armature extending along a first axis, the armature
having a first end and a second end and configured to be slidably
disposed within the case along the first axis; a first coupler to
couple the first end of the armature with the first portion of the
case and a second coupler to couple the second end of the armature
with the second portion of the case; and the second coupler
configured to allow controlled movement between the armature and
the case along a second axis orthogonal to the first axis.
31. An electromechanical transducer comprising: a case having a
first portion and a second portion; and elongate armature extending
along a first axis, the armature slidably disposed within the case
along the first axis and along first and second bearing assemblies;
wherein the bearing assemblies comprising first and second linear
bearing rails attached to first and second ends of the armature,
respectively, and first and second bearing trucks attached to first
and second portions of the case, the first and second bearing
trucks configured to engage the first and second linear bearings,
respectively; wherein the second bearing assembly is configured to
allow controlled movement between the second linear bearing rail
and the second bearing truck along a second axis orthogonal to the
first axis.
32. An active suspension system for a vehicle, the system
comprising: an electromechanical actuator, the actuator comprising:
an outer case having a first portion and a second portion; an
elongate armature extending along a first axis, the armature having
a first end and a second end and configured to be slidably disposed
along the first axis; and a first coupler to couple the first end
of the armature with the first portion of the case and a second
coupler to couple the second end of the armature with the second
portion of the case; wherein the second coupler is configured to
allow controlled movement between the armature and the case along a
second axis orthogonal to the first axis.
33. A method of controlling an electromechanical transducer, the
method comprising: driving an elongate armature defining a first
axis between a pair of couplers back and forth along the first
axis; and configuring the armature and the couplers to permit
movement of the armature along a second axis orthogonal to the
first axis.
34. An apparatus comprising: an electromagnetic transducer
including a stator and an armature defining a first axis; wherein
the armature is driven to ride between a pair of couplers back and
forth relative to the stator along the first axis; wherein the
armature and the couplers are configured to provide a controlled
amount of force in the armature along a second axis orthogonal to
the first axis.
35. The apparatus of claim 34 wherein the armature and the couplers
are configured to provide a controlled amount of tension in the
armature along the second axis.
36. The apparatus of claim 34 wherein the armature and the couplers
are configured to provide a controlled amount of compression in the
armature along the second axis.
37. A method of controlling an electromechanical transducer, the
method comprising: driving an elongate armature defining a first
axis between a pair of couplers back and forth along the first
axis; and configuring the armature and the couplers to provide a
controlled amount of force in the armature along a second axis
orthogonal to the first axis.
38. The method of claim 37, wherein the controlled amount of force
provides a controlled amount of tension in the armature along the
second axis.
39. The method of claim 37, wherein the controlled amount of force
provides a controlled amount of compression in the armature along
the second axis.
Description
TECHNICAL FIELD
[0001] This description relates to electromechanical
transducing.
BACKGROUND
[0002] The present invention relates in general to
electromechanical transducing along a path and more particularly
concerns an along-path, typically linear, controllable force source
for actively absorbing energy from or applying energy to a vehicle
wheel support assembly moving over a rough surface so as to
facilitate significantly reducing forces transmitted to the vehicle
body supported on the wheel support assembly.
[0003] Electromechanical transducing may be used, for example, in
vehicle suspensions. Vehicle suspensions employ a spring and shock
absorber to isolate wheel motion from body motion. Some suspensions
are variable and adaptive to driving conditions. For example, it is
known to use electrically controlled active suspension members,
such as an hydraulic piston actuator containing gas or fluid having
a pressure that can be electrically controlled, to achieve a
predetermined characteristic, such as a hard or soft ride, while
avoiding bottoming.
[0004] An electromagnetic transducer, such as a linear actuator,
can be used in place of or in combination with the springs and/or
shock absorbers and can include an armature mounted within a stator
as described in U.S. Pat. No. 4,981,309 and incorporated here by
reference. The armature can include bearing rails that slide within
bearing trucks attached to the stator.
SUMMARY
[0005] According to a first aspect, the invention features an
apparatus including an electromagnetic transducer having a stator
and an armature which defines a first axis. The armature is driven
to ride between first and second couplers back and forth relative
to the stator along the first axis. The second coupler is
configured to permit movement of the armature along a second axis
orthogonal to the first axis.
[0006] In various embodiments, the apparatus includes an outer case
having first and second portions. The armature can include first
and second ends and configured to be slidably disposed within the
case along the first axis.
[0007] In one example, the first coupler is configured to couple
the first end of the armature with the first portion of the case
and the second coupler is configured to couple the second end of
the armature with the second portion of the case. In another
example, the second coupler is configured to impart high stiffness
to the armature along a third axis orthogonal to both the first
axis and the second axis.
[0008] The first coupler can include a first linear bearing rail
attached to a first end of the armature and a first bearing truck
affixed to a first portion of the case. The first coupler can
include a first linear bearing rail attached to a first portion of
the case and a first bearing truck affixed to a first end of the
armature.
[0009] In various applications, the first bearing rail is slideably
disposed in the first bearing truck. The first bearing truck can be
aligned with the first end of the armature along a surface
substantially parallel to the first axis. The second coupler can
include a second linear bearing rail attached to the second end of
the armature, and a second bearing truck disposed within the second
portion of the case. In one application, the second bearing truck
slideably engages the second portion of the case along the second
axis.
[0010] In one example, the apparatus includes set screws which
extend from one or more of the bearing trucks and ride within slots
disposed along the case to guide the movement of the armature. In
another example, the second bearing truck slideably engages a
recess disposed in the second portion of the case along the second
axis for movement of the second end of the armature along the
second axis.
[0011] The second coupler can also include roller bearings
positioned between the bearing surface and the bearing pockets for
slideable engagement of the second end of the armature within the
second portion of the case along the second axis. In one
application, the second coupler includes roller bearings positioned
between the bearing surface and the bearing pockets for rollable
engagement of the second end of the armature within the second
portion of the case along the first axis. In one example, the
second end of the armature includes a bearing surface to engage a
bearing pocket disposed within the second portion of the case.
[0012] In one application, the apparatus includes roller bearings
positioned between one or more of the ends of the armature and the
case. The couplers can be low-friction blocks, such as delryn
retainers for example, positioned between at least one of the ends
of the armature and the case.
[0013] In one example, the apparatus also includes a third coupler
affixed to the second portion of the case. The third coupler can
include a third bearing truck slideably coupled to the second
bearing rail. The third coupler can also include a surface
substantially parallel to the first axis to provide substantial
alignment to the second coupler. In one application, the third
coupler includes at least one recess disposed along the second
portion of the case.
[0014] In one application, the apparatus includes a first biasing
element and a second biasing element extending from the second end
of the armature to the second portion of the case. The first
element can be configured to provide a first stiffness along a
third axis orthogonal to the first axis and the second axis and the
second element can be configured to provide a second stiffness
along the second axis. In various examples, the first biasing
element and the second biasing element can include a spring, a
magnet, and/or an air bearing.
[0015] According to another aspect, the invention features a
vehicle having an active suspension system, a chassis and at least
one wheel assembly. The wheel assembly includes at least one of the
apparatus described in the first aspect to providing a controllable
force between the wheel assembly and the chassis. The apparatus is
configured such that the first coupler of the armature
substantially faces the front of the vehicle and the second coupler
substantially faces the rear of the vehicle.
[0016] According to another aspect, the invention features a
vehicle having an active suspension system, a chassis and at least
one wheel assembly, and including at least one of the apparatus
described in the first aspect for providing a controllable force
between the wheel assembly and the chassis. The apparatus is
configured such that the asymmetry in the load capacity of the
couplers matches the asymmetry in the applied loads of the
vehicle.
[0017] According to another aspect, the invention features a
vehicle having an active suspension system and including a chassis,
at least one wheel assembly, and at least one of the apparatus
described in the first aspect for providing a controllable force
between the wheel assembly and the chassis. According to another
aspect, the invention features a vehicle having an active
suspension system and including a chassis, and at least two wheel
assemblies, and each wheel assembly having at least one of the
apparatus according to the first aspect for providing a
controllable force between the wheel assembly and the chassis.
[0018] According to another aspect, the invention features an
electromechanical transducer including an outer case having a first
portion and a second portion and housing a stator. The elongate
armature extends along a first axis includes a first end and a
second end and is configured to be slidably disposed within the
case along the first axis. The transducer includes a first coupler
to couple the first end of the armature with the first portion of
the case and a second coupler to couple the second end of the
armature with the second portion of the case. The second coupler is
configured to allow controlled movement between the armature and
the case along a second axis orthogonal to the first axis.
[0019] According to another aspect, the invention features an
electromechanical transducer including a case having a first
portion and a second portion and an elongate armature which extends
along a first axis. The armature is slidably disposed within the
case along the first axis and along first and second bearing
assemblies. The bearing assemblies are configured to include first
and second linear bearing rails attached to first and second ends
of the armature, respectively, and first and second bearing trucks
attached to first and second portions of the case, the first and
second bearing trucks configured to engage the first and second
linear bearings, respectively. The second bearing assembly is
configured to allow controlled movement between the second linear
bearing rail and the second bearing truck along a second axis
orthogonal to the first axis.
[0020] According to another aspect, the invention features an
active suspension system for a vehicle, where the system includes
an electromechanical actuator. The actuator includes an outer case
having a first portion and a second portion, an elongate armature
extending along a first axis, having a first end and a second end
and configured to be slidably disposed along the first axis, a
first coupler to couple the first end of the armature with the
first portion of the case and a second coupler to couple the second
end of the armature with the second portion of the case. The second
coupler is configured to allow controlled movement between the
armature and the case along a second axis orthogonal to the first
axis.
[0021] According to another aspect, the invention features a method
of controlling an electromechanical transducer including driving an
elongate armature which defines a first axis between a pair of
couplers back and forth along the first axis and configuring the
armature and the couplers to permit movement of the armature along
a second axis orthogonal to the first axis.
[0022] According to another aspect, the invention features an
apparatus having an electromagnetic transducer including a stator
and an armature which defines a first axis. The armature is driven
to ride between a pair of couplers back and forth relative to the
stator along the first axis. Both the armature and the couplers are
configured to provide a controlled amount of force in the armature
along a second axis orthogonal to the first axis. In one
application, the armature and the couplers are configured to
provide a controlled amount of tension in the armature along the
second axis. In another application, the armature and the couplers
are configured to provide a controlled amount of compression in the
armature along the second axis.
[0023] According to another aspect, the invention features a method
of controlling an electromechanical transducer including driving an
elongate armature which defines a first axis between a pair of
couplers back and forth along the first axis and configuring the
armature and the couplers to provide a controlled amount of force
in the armature along a second axis orthogonal to the first axis.
In one application, the controlled amount of force provides a
controlled amount of tension in the armature along the second axis.
In another application, the controlled amount of force provides a
controlled amount of compression in the armature along the second
axis.
[0024] Other advantages and features will become apparent from the
description and from the claims.
DESCRIPTION
[0025] FIG. 1 is a combined block-diagrammatic representation of a
vehicle wheel suspension.
[0026] FIG. 2 is a combined block-diagrammatic representation of an
active wheel assembly.
[0027] FIG. 3 is a perspective view of an electromechanical linear
actuator.
[0028] FIG. 4A is a schematic top view of an electromechanical
actuator. FIG. 4B is a detail view of a linear bearing depicted in
the actuator of FIG. 4A.
[0029] FIGS. 5 and 6 are schematic top view of view of an
electromechanical actuator.
[0030] FIG. 7A is a schematic top view of an electromechanical
actuator. FIG. 7B is a detail view of a linear bearing depicted in
the actuator of FIG. 7A.
[0031] FIG. 8A is a schematic top view of an electromechanical
actuator. FIG. 8B is a detail view of a linear bearing depicted in
the actuator of FIG. 8A.
[0032] FIG. 9A is a schematic top view of an electromechanical
actuator housed within a two-part case. FIG. 9B is a detail view of
a linear bearing depicted in the actuator of FIG. 9A.
[0033] FIG. 10 is a schematic side view of an electromechanical
actuator.
[0034] FIG. 11 is an overall view of active vehicle suspension
system.
[0035] Referring to FIG. 1, a suspension assembly 20 for a vehicle
includes a wheel assembly 22 supporting the sprung mass 24 of the
vehicle, typically about one-fourth the total mass of the vehicle,
including the vehicle frame and components supported thereon (not
shown). The sprung mass is connected to the wheel assembly by a
spring-damper 25, which includes a spring element 26 coaxial with a
shock absorber 28. Specifically, a wheel 30 includes a tire 32, and
a hub 34 which is mounted for rotation about an axle 36. A wheel
support assembly 38 connects the axle to the spring-damper assembly
25. The wheel assembly and wheel support assembly are characterized
by an unsprung mass Mw. A brake assembly (not shown) can also be a
component of the unsprung mass. The tire is shown supported by a
road surface 40.
[0036] Referring to FIG. 2, an exemplary active vehicle suspension
assembly 50 includes an electromechanical actuator and a damping
assembly. The sprung mass 24 is connected to a wheel support
assembly 52 by an active suspension actuator 54 which is controlled
by electronic controller 56. A damping assembly including damping
mass 58 connects to wheel support member with a damping spring 60
coaxial with clamping resistance element 62, which can be a shock
absorber, for example.
[0037] Referring to FIG. 3, an example of an electromechanical
actuator, a linear motor 70, is configured for the active
suspension assembly 50 (FIG. 2). Such a suspension assembly is
described in commonly owned U.S. Pat. No. 4,981,309, the contents
of which are incorporated here by reference, as if fully set forth.
The linear motor includes an inside member 72 which is slideably
disposed within an outside member 74. An exposed end of the inside
member includes a bushing 76 pivotally connected to the unsprung
mass (not shown), such as a wheel assembly as described above, for
example. The outside member is pivotally connected at an end
opposite the bushing to support member 78 attached to the sprung
mass, such as the vehicle frame, for example. An outside member
mounting frame 80 is affixed to an outside member pole assembly 82
and includes coils 88. The inside member can include an array of
rectangular magnets 84. The outside member can include linear
bearings 90 that slideably engage bearing rails 92a, 92b to
facilitate relative movement between the inner and outer
members.
[0038] FIGS. 4A to 9 provide schematic top views of an
electromechanical actuator, such as the actuator depicted in FIG.
3, for example. Referring first to FIG. 4A, a bearing system 110
allows an armature 112 to slide freely in the Z-direction as
indicated, relative to an outer case 114, along a linear bearing
assembly 116a and 116b. In one example, the armature 112 is
elongate, and defines a longitudinal axis which extends generally
in the Z-direction. At the same time, the bearing system can
provide for constrained movement or high stiffness in the
Y-direction to prevent the armature from impacting a stator, such
as stacks 118a and 118b, which can be coils 88 (FIG. 3) as
described above. The armature is attached to a pair of couplers.
Couplers may comprise numerous types of bearing assemblies. In one
embodiment, each coupler comprises a linear bearing rail and at
least one bearing truck, where each coupler for example is attached
at opposite ends of the armature. In other embodiments one or more
couplers may comprise other bearing assembly types, such as roller
bearings or magnetic bearings.
[0039] The couplers permit the armature 112 to slide freely
relative to the outer case 114 along a first direction (such as
Z-direction as indicated), while limiting the relative movement of
the armature 112 and the outer case 114 along a second direction
(such as Y-direction as indicated). In one embodiment, the bearing
rails are attached to the armature and the bearing trucks are
attached to the stator. In another embodiment, bearing trucks are
attached to the armature and bearing rails are attached to the
stator. In some embodiments, couplers are fixedly attached to the
stator (or the case housing the stator), such that motion of the
armature in the X direction is constrained. In other embodiments,
one of the couplers is attached to the stator or stator housing in
a manner that allows some degree of relative motion between the
coupler and the stator in the X direction to occur.
[0040] FIG. 4B shows the detailed view of how armature 112 engages
the bearing truck 122a, which applies to the discussion of all
following relevant figures. Specifically, with reference to FIG.
4B, the left side of the armature is attached to linear bearing
rail 120a using screws 111. The bearing rail 120a engages a bearing
truck 122a which is rigidly attached to the case 114 using screws
121. The armature slides freely in the Z-direction.
[0041] Back to FIG. 4A, on the right side of armature, a linear
bearing rail 120b engages a bearing truck 122b and slides freely in
the Z-direction. Bearing trucks 122a, 122b can be rigidly attached
to case 114 and contain ball-bearing assemblies to allow for free
relative motion in the Z-direction between the each rail and the
corresponding truck.
[0042] If the bearing trucks are both rigidly mounted to case as
depicted in FIG. 4A, then the mechanical assembly includes more
constraints than required for dynamic equilibrium and is
overconstrained in the X-direction. Unless the case and armature
are machined with equally matched tolerances, the constraints will
load the armature in either tension or compression along the
X-direction. By careful design of the armature and case it is
possible to purposely apply force to the armature 112, thereby
placing the armature in either tension or compression. Depending
upon the application, such a design might be desirable. For
example, placing armature in tension in the X-direction can
increase the perceived stiffness of armature in the Y-direction,
reducing the potential of the armature impacting the stacks 118a,
118b. Placing armature into tension or compression also can
increase the possibility of friction within the bearing trucks when
the armature is sliding in the Z-direction. In order to eliminate
this source of friction, the overconstraint in the X-direction can
be reduced.
[0043] Referring to FIG. 5, a bearing system 128 can address the
overconstraint condition with modifications to the right-side
bearing system, but it should be understood that similar
modifications could be made to the left-side bearing system or both
the right and left-side bearing systems. The armature 112 is
allowed to slide freely in the Z-direction relative to the case
129. A right-side bearing 130 can provide for free motion in the
Z-direction, high stiffness in the Y-direction, and low stiffness
in the X-direction. Biasing elements 132a and 132b are elements
providing high stiffness in the Y-direction and biasing element 134
is an element providing low stiffness in the X-direction. In
practice, it is possible to implement these biasing elements with a
variety of devices including mechanical components, such as
springs, magnetic components, and/or an air bearing system.
[0044] Another example of a bearing system 135 is shown in FIG. 6,
including a left-side bearing truck 136 shown rigidly attached to a
case 138 using screws 140. A right-side bearing truck 142 is shown
"floating" relative to the case 138 using set-screws 144. By
appropriately designing the width of the case 138 and the width of
the armature 112, a predetermined gap 146 can be established
between the case 138 and the bearing truck 142. Designing bearing
truck pockets 148a, 148b to be slightly oversized relative to
bearing truck 142 establishes stiffness along the Y-direction. As
the movement of the right-side bearing is constrained in the
Y-direction but is permitted along the X-direction, this assembly
provides for substantially high stiffness in the Y-direction and
substantially no stiffness in the X-direction. As such, the
overconstraint condition is addressed and the movement of the
armature 112 in the Z-direction in substantially unrestricted.
[0045] In another implementation, a bearing system 149 shown in
FIG. 7A, includes the left-side bearing truck 136 rigidly attached
to a case 150 using screws 140. The right-side bearing assembly
includes a bearing surface 152 connected to the right side of the
armature 112. To prevent the armature 112 from contacting stacks
118a and 118b, while moving in the Z-direction, roller bearings
154a, 154b may be used. FIG. 7B illustrates further details of the
engagement of the armature 112 and the roller bearings 154a, 154b
and the movement of the armature 112 along the Z-direction. To
achieve high Y-direction stiffness, bearing pockets 156a, 156b are
designed to be at least slightly larger than the thickness of
armature 112 plus the thickness of the roller bearings 154a, 154b.
Referring back to FIG. 7A, a gap 158 can be established between the
side surface 151 of case 150 and the side surface 153 of the
right-side bearing assembly which significantly reduces stiffness
in the X-direction. As with the bearing assembly 135 of FIG. 6,
this assembly provides for substantially high-stiffness in the
Y-direction and substantially reduced or no stiffness in the
X-direction. In one example, the left-side bearing assembly
implemented by bearing truck 136 and bearing rail 120a provides
enough stiffness in the Y-direction such that the right-side
bearing assembly does not need to provide any additional stiffness
for the armature. In this example, roller bearings 154a, 154b can
be eliminated.
[0046] In another example, a bearing system 159 shown in FIG. 8A,
includes the left-side bearing truck 136 rigidly attached to a
first portion of the case 150 using screws 140. A right end of the
armature 112 is connected to a bearing rail 160 with a spring 162.
Bearing truck 164 is then rigidly attached to case 150 using screws
166. By adjusting the stiffness of spring 162, it is possible to
adjust the level of friction that develops when armature 112 slides
in the Z-direction. Spring 162 can represent the compliance of
armature 112 and not be a physically separate element. Guides 170a,
170b can be used to provide additional stiffness in the
Y-direction. In one example, as shown in FIG. 8B, low-friction
blocks 172a, 172b such as delryn retainers, for example, are
rigidly attached to the guides 170a and 170b to provide
substantially high-stiffness in the Y-direction and substantially
no stiffness in the X-direction between guides 170 and armature
112.
[0047] In another example, a bearing system 174 shown in FIG. 9A,
includes the left-side bearing truck 136 rigidly attached to a left
case-half 176 using screws 140. Similarly, right-side bearing truck
178 is shown rigidly attached to a right case-half 177 using screws
180. Compliance in the X-direction is provided by springs 182a,
182b extending between the left and right case-halves 176, 177.
Springs 182a, 182b can represent the compliance of the case-halves
and not be physically separate components. Referring to FIG. 9B,
guides 184a, 184b and low friction blocks 186a, 186b such as delryn
retainers, for example, can be provided for additional Y-direction
stiffness.
[0048] Without loss of generality, it should be understood that
more than one bearing truck can be provided to engage the bearing
rail extending along the Z-direction to provide additional
stiffness in the Y-direction. Referring to FIG. 10, for example, a
bearing system 188 includes a bearing rail 190 which slides in the
Z-direction relative to case 192. Bearing trucks 194 and 196 can
represent either left-side or right-side bearings in the
descriptions of FIGS. 1 through 6. As such, bearing trucks 194, 196
can be either fixed to the case 192 or floating relative to the
case. In the bearing system 188, bearing trucks 194, and 196 can be
aligned in the Z-direction. This is accomplished using reference
surface 200 (which forms one side of the bearing pocket). Reference
surface 200 could be machined in one operation so as to guarantee
the alignment of the two trucks.
[0049] Referring to FIG. 11 and in one example, the actuators 210
form part of an integrated and active suspension control system for
a vehicle 212. Actuators 210 are integrated at each wheel of the
front and rear suspension systems 214, 216, respectively, of the
vehicle as described with reference to FIG. 2. The actuators 210
can form part of the structural suspension linkage connecting the
wheel assembly to the vehicle frame. The load capacity of the
actuators 210 is asymmetric in that the load of the bearing is
stronger in compression than in tension in a fore-aft direction.
The dynamic loads applied to the bearings by the vehicle are
asymmetric in that the applied loads are substantially greater
during braking than acceleration. The actuators can be positioned
within the vehicle to match the asymmetry in the load capacity of
the bearing with the asymmetry in the applied loads of the vehicle.
In one example, a first side of the actuator 220 including a fixed
or rigidly attached bearing truck, such as the left-side bearing
truck 136 (FIG. 6) is positioned toward the front of the vehicle
and a second side of the actuator 222 including a floating bearing
truck, such as the right-side bearing truck 142 (FIG. 6) is
positioned toward the rear of the vehicle.
[0050] A number of embodiments of the invention have been
described. Nevertheless, it will be understood that various
modifications may be made without departing from the spirit and
scope of the invention. For example, although the described
applications for the bearing systems include active vehicle
suspensions, other applications that require an electrically
controllable relative force between sprung and unsprung masses, are
contemplated. Accordingly, other embodiments are within the scope
of the following claims.
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